Some 150 schools with more than 12,000 pupils have been forced to close due to the deadly attacks in Niger’s southeast Diffa region, the United Nations said Friday.

Most of the affected schools are near Lake Chad and on the banks of the Yobe River, which marks the border between Niger and Nigeria, the U.N.’s Office for the Coordination of Humanitarian Affairs (OCHA) said in a statement.

The agency said 151 schools with a total of 12,631 pupils had closed due to “insecurity that has sparked the absence of teachers and panic in the population”.

“The pupils are now at camps for displaced people,” the agency said, adding that there are no schools at the camps.

Citing a source in Niger’s government, OCHA also said that 47,000 of Diffa’s 500,000 residents had been forced to flee their homes since February, when Boko Haram launched a string of deadly attacks.

Numerous local schools closed following Boko Haram’s first attacks in the country in February, with more following suit following a recent surge in assaults by the Nigeria-based militant group, a local official told AFP.

Thirteen people were killed and three injured in an attack on the Diffa village of Ala last week, local officials said.

Niger’s government has been working with the U.N. and other partners on a plan intended to allow children to go back to their studies in safer locations by the end of November.

Boko Haram has carried out several bloody attacks in Diffa, as the army struggles to contain the group’s regional advances.

Cameroon, Chad and Niger have formed a military alliance with Nigeria and Benin to battle the militants, who this year declared allegiance to the ISIS.

Boko Haram has been hit hard by the multinational offensive, losing territory, but it has launched attacks and bombings in response.